Apparatus for programming movement of a cart

ABSTRACT

A wheeled cart is controlled to take a particular path under the direction of movement information stored on a tape recorder. The information on the tape recorder is initially placed there as the cart is manually directed over the desired path with a control means. The prescribed path for the cart can be altered at any time by changing the recorded information in the same manner as initially provided.

United States Patent 1191 Geislinger 1 Feb. 5, 1974 [5 1 APPARATUS FORPROGRAMMING 3,072,833 1/1963 Kerr et al 318/568 MOVEMENT OF A CART3,340,950 9/1967 Hopengartem. 180/105 R 3,356,918 12/1967 wllllamS318/162 x Inventor: Eric ge 13773 SW 3,563,327 2/1971 Mier ISO/6.5

Electric St., Beaverton, Oreg. 97005 22 l d; Sept, 7 197 PrimaryExaminer-Kenneth H. Betts Assistant Examiner-Leslie J. Paperner [21]Appl. No.: 178,116 Attorney, Agent, or FirmKlarquist, Sparkman,

Campbell, Leigh, Hall & Whinston [52] US. Cl 180/65, 56/10.2, 56/DIG.15,

172/3, 180/791, 318/162 [57] ABSTRACT {g l' A wheeled cart is controlledto take a particular path 56 under the direction of movement informationstored /l0.2, DIG. 15, 172/3, 318/162, 568, 587

on a tape recorder. The information on the tape recorder is initiallyplaced there as the cart is manually [56] References Cited directed overthe desired path with a control means. UNITED STATES PATENTS Theprescribed path for the cart can be altered at any 3,061,035 10/1962King l80/79.1 time by changing the recorded information in the Huston eta]. X ame manner as provided 3,481,417 12/1969 Jarret et a1 180/653,650,097 3/1972 Nokes 56/l0.2

3 Claims, 7 Drawing Figures APPARATUS FOR PROGRAMMING MOVEMENT OF A CARTBACKGROUND OF THE INVENTION The present invention relates to aprogrammed cart or vehicle, and particularly to a cart or vehicle whichcan be easily directed in advance to follow any arbitrary, predeterminedpath by the user of the vehicle.

Various proposals have been made for guiding a cart or vehicle along aspecified route or path, e.g., a tractor moving along aprescribedpathway without manual assistance. Various methods haveincluded the utilization of buried objects in the ground with which themovable cart may align itself, or a mechanical linkage or cam which willcause the apparatus to repeat a given series of movements.Unfortunately, the programming is then noteasily alterable or adjustablefor individual conditions, and at least involves physical movement ofreference elements, or replacing of a cam or similar part.

SUMMARY OF THE INVENTION According to the present invention, the programof a programmable cart is alterable at will. The program is initiallyprovided by manually directing movement of the cart along a prescribedpath, as for instance the desired route ofa lawn mower in mowing a yard.Not only are manually directed control instructions applied to themotive means of the cart, but at the same time these instructions arerecorded for future use. After the cart has been manually directedthrough its predetermined course, the same recorded instructions areapplicable to the motive means for repeating the same course.

Recorder means are employed which permit change in the prescribed pathat will, as by a manually directing.

cart along another for recording a different path, to which the cartsmotive means may then be responsive. For instance, in a preferredembodiment, magnetic tape recorder means are provided whereby any numberof different paths may be recorded and/or erased, resulting in optimumflexibility of the cart movement.

Also, the present invention allows considerable experiv mentation oralteration in the paths which may be employed by the cart, i.e., forselecting the path that is the most satisfactory for instance in cuttinggrass over a particular terrain.

Accordingly, it is an object of the present invention to provide animproved apparatus for programming movement of a cart, allowing maximumflexibility in altering programmed movement to any desired course.

It is another object of the present invention to provide an improvedapparatus for programming movement of a cart wherein the programming isaccomplished by manually directing the cart over a desired course.

It is a further object of the present invention to provide improvedapparatus for programming a cart wherein substantially any number ofroutes may be programmed for the cart and wherein such routes arechangeable at will.

It is further object of the present invention to program movement of acart wherein the programming may be changed at any time through manualdirection of the movement of such cart.

The subject matter which I regard as my invention is particularlypointed out and distinctly claimed in the concluding portion of thisspecification. The invention,

however, both as to organization and method of operation, together withfurther advantages and objects thereof, may best be understood byreference to the following description taken in connection with theaccompanying drawings wherein like reference characters refer to likeelements.

DRAWINGS FIG. I is a perspective view of a programmable cart, accordingto the present invention, in the form of a lawn mower;

FIG. 2 is a block diagram of a first circuit embodiment of the apparatusaccording to the present invention for programming movement of a cart;

FIG. 3 is a more detailed schematic diagram of a portion of the FIG. 2circuit;

FIG. 42 is a schematic diagram of an alternative portion of the FIG. 2circuit;

FIG. 5" is a partial plan view of a preferred recorder apparatusaccording to the present invention;

FIG. 6 is a waveform chart illustrating operation according to analternative embodiment of the present invention; and

FIG. 7 is a block diagram of an alternative circuit embodiment ofapparatus according to the present invention for programming movement ofa cart.

DETAILED DESCRIPTION Referring to the drawings and particularly to FIG.1, a cart is illustrated in the form of a lawn mower of the rotary typehaving the rear wheels 10 and 12 and front wheels 14 and 16. In thiscase the front wheels are motor driven by means of electric motors I8and 20, respectively, but it is understood the motors may alternativelydrive the rear wheels rather than the front wheels. The motors arecontrolled and empowered from cabinet 22which may include a motor powersupply. Control leads 24 are connected between cabinet 22 and furthercontrol devices in the form of one or more potentiometers, ashereinafter more fully described, adapted for mounting upon the upperhandle of the lawn mower (not shown). While a lawn mower is illustratedfor purposes of explaining the invention, it is understood that the cartmay equally well comprise a vacuum cleaner, floor polisher, toy or othersimilar vehicle which is movable upon wheels.

Referring to FIG. 2 illustrating a preferred embodiment of the presentinvention, the aforementioned potentiometers for mounting upon the lawnmower upper handle are illustrated at 26 and 28, respectively, and eachcomprises a voltage divider together with grounded resistor 30 connectedto a center tap between potentiometers 26 and 28. The remaining end ofthe potentiometer 26 is coupled to the output of oscillator 32 while theremaining terminal of potentiometer 28 is connected to the output ofoscillator 34. Oscillators 32 and 34 are of conventional constructionand provide outputs at frequencies f and f respectively. In a typicalinstance, these frequencies are suitably 600 Hertz and 1,000 Hertz.

As illustrated in FIG. 2, the potentiometers movable taps 36 and 38 arecontrollable together by a single handle indicated by dashed line 40.The arrangement is such that simultaneous movement of potentiometer tapsin a first direction, i.e., upwardly on the drawing, increases theoutput of oscillator 32 at tap 36 while decreasing the output ofoscillator 34 at tap 38. The reverse movement produces the reverseresult. The taps are connected together at terminal 42 at the top of afurther potentiometer 44, which is also mounted on the lawn mower upperhandle and connected via control leads 24 in FIG. 1. The oscillatoroutputs are thus combined and the combined signal is adjusted inamplitude by means of the movable tap 46 of potentiometer 44. Themovable tap 46 of potentiometer 44 is employed principally to controlthe over-all speed of the cart, while the handle indicated at 40 is tocontrol its direction of movement.

The movable tap 46 is connected to the recording input of a taperecorder 48, and also via switch 50 to the playback output of taperecorder 48, as well as to the inputs of filters 52 and 54. Filters 52and 54 are tuned to the frequencies f and f respectively, i.e., thesefilters comprise resonant or bandpass filters for specifically detectingthese frequencies. Preferably, these filters comprise active filters ashereinafter more fully described. The output of filter 52 drives poweramplifier 56 which provides the power for left motor through rectifier58. Similarly, amplifier 60 provides the power for right motor 18 viarectifier 62. It is understood that amplifiers 56 and 60 comprise poweramplifiers sufficiently empowered and of sufficient output for drivingthe motors 20 and 18. The amplifier outputs, being AC, are rectified byrectifiers 58 and 62 before application to the motors 20 and 18 whichare suitable DC motors. Alternatively, the output of amplifiers 56 and60 may be employed in a well known manner to control the application ofdirect current power from another source to the motors 20 and 18.

Recorder 48 is suitably a commercially available cassette type taperecorder or the like, employing magnetic tape as a recording medium. Itis understood the recorder has a conventional record input and aplayback" output, and conventional means for switching between therecord and playback functions.

Considering operation of the FIG. 2 circuit, the cart is first operatedmanually over a predetermined path by controlling potentiometer movabletaps 36 and 38. The tape recorder is set to a record mode at this timeand switch 50 is suitably closed whereby the combined output at terminal42 is recorded on recorder 48 while it is also coupled to filters 52 and54. As the potentiometer taps 36 and 38 are moved upwardly by the commonhandle indicated at 40, the amplitude of the oscillator signal componentof frequency f, will increase at terminal 42, while the amplitude of thesignal component at frequency f will decrease. Since filter 52 isattuned to frequency f,, a greater amplitude signal at that frequencywill provide a larger drive to left motor 20 via amplifier 56 than isprovided at frequencyf via filter 54 and amplifier 60 to motor 19.Consequently, the cart moves forwardly, but motor 20 turns more rapidlythan motor 18, causing the cart to turn to the right. If, on the otherhand, the taps 36 and 38 are moved downwardly by the handle indicated at40, right motor 18 will receive the greater input, and the cart willturn to the left. With taps 36 and 38 both at midscale, the cart willmove directly ahead.

Alternatively, potentiometers 26 and 28 can be so designed, i.e., intaper, so that the center position of each potentiometer supplies amaximum output at terminal 42. Then, rotation of the potentiometers bymeans of the handle indicated at 40 functions only to slow down one ofthe motors while the speed of the other motor remains substantiallyconstant.

While the cart is thus directed over any desired path by means of thecommon control handle indicated at 40, the same signals are recorded onthe magnetic tape medium of recorder 48. When the desired path for thecart is completed, recorder 48 may be turned off and the tape may berewound in the conventional manner to its starting position. Thereupon,switch 50 is opened and the tape recorder is switched to the playbackmode. The tape recorder will now provide the identical combinationsignal to filters 52 and 54 which was theretofore delivered at terminal42. Consequently, the cart will follow the original predeterminedmovements directed by the initial operation of the control handle as thecart was first moved over such path.

Thus, if the cart is a lawn mower as illustrated in FIG. 1, the lawnmower may be first directed over the desired path by employing thecontrol handle indicated at 40 with the tape recorder switched to therecord mode. When the path is complete, the recorder is switched off. Ata later time, when it is desired that the lawn mower follow the originalrecorded path for cutting the same lawn, the mower is placed at the samestarting position pointing in the same direction, and the tape recorder48 is operated in the playback mode. The mower will then follow thisrecorded path. At the end of the recording, the oscillator signals willno longer be present at the output of the recorder, and the machine willstop.

The present invention is quite flexible in that the cart may bereprogrammed at any time to follow a different path. Thus, if it isdesired to change the path which the cart takes, it is only necessary torewind the tape, switch recorder 48 to record, and guide the cart bymeans of the handle indicated at 40 over a different path. Switch 50 isclosed at this time. The new path information will be recorded in placeof the old on the tape recorder. Then the cart is ready to repeat thenewly recorded path in the same manner as indicated above.Alternatively, more than one path may be recorded on the same tape asdesired, with a nonrecorded length of tape being left betweeninformation relating to different paths such that the cart will stop atthe end of the desired path. The particular path of movement is thenselected by selection of the proper recorded location on the tape, and,of course, may be changed at any time partially or completely byrewriting the magnetic tape with the potentiometer control ashereinbefore mentioned.

It is apparent that with the usual tape recorder, e.g., with a cassetterecorder, an individual tape is easily removed and replaced with aseparate tape. Thus, the cart is made adaptable for operating over manyalternative paths recorded at different times. Furthermore, a taperecorder may be employed with an adjustable amplitude output and withspeed controls for adjusting the speed of tape transport. In suchinstance, the cart may be moved ovrer a given path relatively slowly byhand, after which the tape recorder playback tape speed and signaloutput amplitude is adjusted for causing the cart to move over thedesired path at a greater speed.

Although passive filter networks may be employed for filters 52 and 54,active filters are to be preferred because of the higher O which can beattained therewith. Referring to FIG. 3, illustrating such a filter, thecircuit includes an amplifier 64 having plus and minus differentialinputs, and a common output connected to the terminal designated E Thecircuit is connected in operational amplifier fashion and includes afirst feedback resistor R, connected between the output and the negativeor inverting input. An input impedance 2, is connected between the inputfilter terminal where the input E is applied and the negative amplifierterminal. This impedance Z, comprises an RC circuit including a seriesconnected resistor R, and capacitor C A second feedback resistor R isconnected between the amplifier output and the positive or non-invertinginput of amplifier 64. Moreover, a shunt impedance Z is disposed betweenthe positive input of the amplifier and ground. This shunt impedancecomprises an RC circuit including the parallel combination of resistor Rand capacitor C The voltage across the combination is E, which, in thisparticular instance, is employed as the actual output of the filter forapplication to amplifiers 56 or 60.

It can be shown that the filter circuit transfer function T(s) E /E [Z/(Z /K) Z where K =RA/RB.

If 2, and Z are chosen to be as indicated in FIG. 3, i.e., the seriesand parallel combinations of resistance and capacitance as shown, and ifthe resistors are respectively made equal to the same value R, while thecapacitors are made equal to the same value, C, then This equation isthe same form as the transfer function between the output and the inputvoltage of an R-L-C circuit, such as illustrated in FIG. 4 (but furtherincluding a load resistor). In other words, the transfer function issubstantially the same as that of a resonant circuit with a centerfrequency, w, l/RC. In a less preferred circuit form, the filters 52 and54 may each comprise the series resonant circuit of FIG. 4 includingrespective inductances 66 and capacitors 68, tuned, of course, to therespective frequencies f, and f An alternative embodiment will beconsidered with the aid of FIG. 5, illustrating a portion of a magnetictape recorder such as referred to at 48 in FIG. 2. This tape recorderincludes tape reels 70 and 72 which alternately form payout and takeupreels for magnetic tape medium 74. During recording and playback thetape moves from reel 70 onto reel 72. In the FIG. 5 embodiment, a write"head 76 is utilized in the conventional manner for recording informationon the tape and is accordingly connected by circuit means within thetape recorder 48 to the movable tap 46 in FIG. 2. Magnetic read head 78provides the output of the tape recorder through circuit means withinrecorder 48 in FIG. 2 for application to the inputs of filters 52 and54. Head 78 may also be termed a monitor head. This arrangement replacesthe conventional tape recorder arrangement where the same head isemployed for both reading and writing, that is to say, recording andplaying back. In utilizing the embodiment of FIG. 5, the switch 50 inFIG. 2 is eliminated together with the connections thereto from therecorder input and output. The read head 78 drives playback circuitrywithin the recorder 48 at all times, and an output is always producedfor application to filters 52 and 54. Thus, when the cart is under thecontrol of the handle indicated at 40, a direct connection is notrequired to the filters 52 and 54 via switch 50, but rather the inputdirective information is recorded on tape 74 in FIG. 5 and immediatelyread by read head 78.

When the cart is controlled by the handle indicated at 40, the combinedsignal at terminal 42 is transcribed on the tape by write head 76. Thena short time later, determined by the time required for the tape to passbetween heads 76 and 78, an output is produced from read head 78 foroperating motors 20 and 18 via the filter and amplifier circuitry.Although a slight delay thus occurs in the control of the cart, thismode of operation eliminates the possibility of the recorder failingfaithfully to reproduce the original path. Thus, when the controlsignals from terminal 42 are at all times passed through the recorder,even for producing the original movements of the cart, such movementswill be faithfully and accurately reproduced at a subsequent time. Thisarrangement thus adapts the invention for use employing tape recorderswhich do not necessarily have linear recording and reproductioncharacteristics.

Another embodiment according to the present invention is illustrated inblock diagram form in FIG. 7. In this case, a single oscillator 80 isprovided which supplies an output at a predetermined audio frequency,and such oscillator may conveniently comprise a transistor or vacuumtube phase shift oscillator. For instance, the oscillator illustratedincludes a transistor 81 provided with a feedback phase shift network83. The power supply for the oscillator comprises a battery shunted bypotentiometer 83 having a movable tap 87 which is grounded. It isunderstood that potentiometer 83 is conveniently mounted for controllingmovement of the cart, as by placing the same on the upper handle in caseof a lawn mower embodiment. The battery 85 empowers the active elementsuch as the transistor 81 of the oscillator 80 in the usual manner viaload resistor 89, but the oscillator circuitry is not returned to groundat a point other than the movable tap 84 of potentiometer 82. Referringto the waveform chart of FIG. 6, showing two example outputs of theoscillator, the sine wave 98 illustrates the oscillator output derivedat the output terminal of the oscillators active element, e.g., thecollector of transistor 81, when the center tap 87 is moved towards thenegative terminal of battery 85. Under such circumstances, the DC levelof the oscillator output will be relatively positive with respect toground since the negative terminal of battery 85 is close to ground. Onthe other hand, if the movable terminal 87 is moved upwardly toward thepositive terminal of battery 85, the oscillator output will berelatively negatively biased as illustrated by waveform in FIG. 6.

In the embodiment of FIG. 7, the output of oscillator 80 is coupled torecorder 82 and via switch 84 (when closed) to the playback output ofrecorder 82. Recorder 82 may comprise a conventional cassette taperecorder, but must be direct coupled and adapted for transcribing notonly the oscillatory output of oscillator 80, but also the DC levelthereof. The playback output of recorder 82 is coupled via oppositelypoled diodes 86 and 88 to the inputs of direct coupled amplifiers 94 and96, respectively. Amplifiers 94 and 96 drive left DC motor 20 and rightDC motor 18', corresponding to the motors 18 and 20 in the previousembodiment. Diode 86 is connected with its anode coupled to the input ofamplifier 94, while diode 88 has its cathode coupled to the input ofamplifier 96. The input of amplifier 94 is shunted to ground by means ofcapacitor 90, while the input of amplifier 96 is similarly shunted toground by capacitor 92. It should be noted in passing that the recorder48 in FIG. 2 need not be direct coupled, and neither do amplifiers 56and 60 have to be direct coupled.

Considering operation of the FIG. 7 circuit, if switch 84 is closed andpotentiometer movable tap 87 is moved downwardly towards the negativeterminal of battery 85, for producing an output similar to waveform 98in FIG. 6, the diode 88 will conduct due to the positively biasedsignal. Capacitor 92 smooths the AC content of the waveform, providingan average level thereof which is amplified by amplifier 96 and appliedto right motor 18'. Consequently, an output for amplifier 96 is presentwhereby right motor 18' will rotate causing the cart to turn to theleft. If, on the other hand, the potentiometer tap 87 is moved upwardlycausing the oscillator 80 to produce a waveform similar to thatindicated at 100 in FIG. 6, diode 86 will couple the signal viaamplifier 94 to left motor causing the cart to turn in a right-handdirection. At the same time, the same information is recorded onrecorder 82. In the case of the FIG. 7 embodiment when the movable tap84 is located at mid-range, both rectifiers 86 and 88 will produce ahalf wave rectified output stored temporarily on capacitors 90 and 92for causing the cart to move straight ahead through energization of bothmotors l8 and 20. The same information may be played back at asubsequent time with switch 84 open and with the recorder switched tothe usual playback mode. As in the previous embodiment, the informationin the recorder may be altered at any time by running the cart over adifferent path by means of movable tap 84, and the cart is thenprogrammed to follow this different path.

In the case of the FIG. 7 embodiment, it is understood that amplifiers94 and 96 have a low enough resistance input to provide for slowdischarge of capacitors 90 and 92. The inputs of amplifiers 94 and 96tend to follow the level of the oscillator output, i.e., the biasthereof, without being sensitive to the individual oscillator outputcycles.

While only two oscillators are illustrated in the case of the FIG. 2preferred embodiment, it is appreciated that other oscillators can besimilarly coupled to terminal 42, and other filter and amplifiercircuits coupled to the output of tape recorder 48 forperforming variousother functions such as initiating rewind of the tape, transferringcontrol to another tape recorder, turning the equipment on or off, etc.

While I have shown and described several embodiments of my invention, itwill be apparent to those skilled in the art that many changes andmodifications may be made without departing from my invention in itsbroader aspects. I therefore intend the appended claims to cover allsuch changes and modifications as fall within the true spirit and scopeof my invention.

What is claimed is:

1. Apparatus for programming movement of a cart, said apparatuscomprising,

motive means for said cart coupled to wheels thereof for determining thedirection of movement thereof, control means for selectively controllingsaid motive means for determining the movement of said cart in a patharbitrarily selected by said control means,

first and second oscillator circuits providing first and second outputswherein said control means effects comparative amplitudes of the outputsof said first and second oscillator circuits to which said motive meansare responsive for effecting a change in direction of movement of thecart in accordance with the relative outputs of said oscillatorcircuits,

a recorder means provided with a magnetic recording medium adaptable forcontinuously recording information provided by the outputs of said firstand second oscillator means according to said comparative amplitudes ofthe outputs of said first and second oscillator circuits duringoperation of said cart as said cart moves in said path for establishinga recording on the magnetic recording medium representative of suchpath,

wherein the outputs of the first and second oscillator circuits areadded before recording, and wherein said control means further includesmeans for regulating the total amplitude of the added signal forcontrolling the speed of said cart, and means for coupling an output ofsaid recorder means to said motive means so that said motive means isalternatively controllable by said recording medium for subsequentlyoperating said motive means to control the direction of said cart forsubstantially duplicating the path previously taken.

2. Apparatus for programming movement of a cart,

said apparatus comprising:

motive means for said cart coupled to wheels thereof for determining thedirection of movement thereof,

control means for selectively controlling said motive means fordetermining the movement of said cart in a path arbitrarily selected bysaid control means,

first and second oscillator circuits providing first and second outputswherein said control means effects comparative amplitudes of the outputsof said first and second oscillator circuits to which said motive meansare responsive for effecting a change in direction of movement of thecart in accordance with the relative outputs of said oscillatorcircuits,

a recorder means provided with a magnetic recording medium adapted forcontinuously recording information provided according to saidcomparative amplitudes of the outputs of said first and secondoscillator circuits during operation of said cart as said cart moves insaid path for establishing a recording on the magnetic-recording mediumrepresentative of such path,

wherein the outputs of the first and second oscillator circuits areadded before recording,

and means for coupling an ouput of said recorder means to said motivemeans so that said motive means is alternatively controllable by saidrecording medium for subsequently operating said motive means to controlthe direction of said cart for substantially duplicating the pathpreviously taken.

3. Apparatus for programming movement of a wheeled cart, said apparatuscomprising:

motive means for said cart coupled to the wheels thereof by means ofwhich movement of said cart is determined, including propulsion of saidcart in a generally forward direction, said motive means comprisingfirst and second motor means coupled to drive respective wheels of saidcart,

9 10 a recorder means having a recording medium for which said cart canbe subsequently responsive,

bearing movement information representative of said outputs of saidfirst and second oscillator cirthe CQUYSC of movement for Said cuitsproviding the recording of information in said means for coupling saidrecorder means to said morecorder means,

five for'causing said can to follow a P and means in circuit with saidfirst and second motor termmed path m accordance with Said infifrmatiommeans responsive to the frequencies respectively of manually operablecontrol means for selectwely said first and second oscillators fordetermining viding electric control values, said motive means beingselectively responsive to said electrical control values for directing adifferent path of movement for said cart, including first and secondoscillator circuits providing first and second outputs wherein saidcontrol means effects comparative amplitudes of the outputs of saidfirst and second movement of said first and second motor means, whereinsaid frequency responsive means each comprise an active filter circuitincluding an operational amplifier having a pair of differential inputsand a pair of feedback impedances coupled respectively thereto, a firstRC series circuit for coupling a filter circuit input to an invertinginput of said oscillator circuits, 5 means for at the same time couplingsaid control ampllfief, and a Parallel RC clrcult coupled to a means tosaid recorder means for recording moven e g inpu of Said amplifier nd acoss ment information representative of said different which the filteredoutput is taken. path on the recording medium in the recorder to PatentNo. 3,739 r Dated February 5, 1974 Inventor(s) Eric L Geislinger It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 3, lines 29-30, "suitable" should be -suitably-.

Column 3, line 56 "motor 19" should be --motor l8-.

Column 4, line 59 "ovrer" should be -over--.

Column 8, line 45 (claim 2 line 16) "adapted" should be -adaptable-.

Signed and sealed this 17th day of September 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents F'JRM PO OSO (10-69) uscoMM-Dc 6O376-P69 U45. GOVERNMENTPRINTING OFFICE: 1969 O365'334 UNITED STATES PATENT OFFICE CERTIFICATEOF CORRECTION Patent No. 3,789,939 D t d February 5, 1974 Inventor(s)Eric L. Geislinger It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 3, lines 29-30, "suitable" should be suitably-.

Column 3, line 56 "motor 19" should be --motor l8-.

Column 4, line 59, "ovrer" should be --over.

Column 8, line 45 (claim 2 line 16) "adapted" should be -adaptable-.

Signed and sealed this 17th day of September 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSIiALL DANN Attesting Officer Commissioner ofPatents Q U.S. GOVERNMENT PRINTING OFFICE: 1959 0-366-1

1. Apparatus for programming movement of a cart, said apparatuscomprising, motive means for said cart coupled to wheels thereof fordetermining the direction of movement thereof, control means forselectively controlling said motive means for determining the movementof said cart in a path arbitrarily selected by said control means, firstand second oscillator circuits providing first and second outputswherein said control means effects comparative amplitudes of the outputsof said first and second oscillator circuits to which said motive meansare responsive for effecting a change in direction of movement of thecart in accordance with the relative outputs of said oscillatorcircuits, a recorder means provided with a magnetic recording mediumadaptable for continuously recording information provided by the outputsof said first and second oscillator means according to said comparativeamplitudes of the outputs of said first and second oscillator circuitsduring operation of said cart as said cart moves in said path forestablishing a recording on the magnetic recording medium representativeof such path, wherein the outputs of the first and second oscillatorcircuits are added before recording, and wherein said control meansfurther includes means for regulating the total amplitude of the addedsignal for controlling the speed of said cart, and means for coupling anoutput of said recorder means to said motive means so that said motivemeans is alternatively controllable by said recording medium forsubsequently operating said motive means to control the direction ofsaid cart for substantially duplicating the path previously taken. 2.Apparatus for programming movement of a cart, said apparatus comprising:motive means for said cart coupled to wheels thereof for determining thedirection of movement thereof, control means for selectively controllingsaid motive means for determining the movement of said cart in a patharbitrarily selected by said control means, first and second oscillatorcircuits providing first and second outputs wherein said control meanseffects comparative amplitudes of the outputs of said first and secondoscillator circuits to which said motive means are responsive foreffecting a change in direction of movement of the cart in accordancewith the relative outputs of said oscillator circuits, a recorder meansprovided with a magnetic recording medium adapted for continuouslyrecording information provided according to said comparative amplitudesof the outputs of said first and second oscillator circuits duringoperation of said cart as said cart moves in said path for establishinga recording on the magnetic recording medium representative of suchpath, wherein the outputs of the first and second oscillator circuitsare added before recording, and means for coupling an ouput of saidrecorder means to said motive means so that said motive means isalternatively controllable by said recording medium for subsequentlyoperating said motive means to control the direction of said cart forsubstantially duplicating the path previously taken.
 3. Apparatus forprogramming movement of a wheeled cart, said apparatus comprising:motive means for said cart coupled to the wheels thereof by means ofwhich movement of said cart is determined, including propulsion of saidcart in a generally forward direction, said motive means comprisingfirst and second motor means coupled to drive respective wheels of saidcart, a recorder means having a recording medium for bearing movementinformation representative of the course of movement for said cart,means for coupling said recorder means to said motive means for causingsaid cart to follow a predetermined path in accordance with saidinformation, manually operable control means for selectively providingelectric control values, said motive means being selectively responsiveto said electrical control values for directing a different path ofmovement for said cart, including first and second oscillator circuitsproviding first and second outputs wherein said control means effectscomparative amplitudes of the outputs of said first and secondoscillator circuits, means for at the same time coupling said controlmeans to said recorder means for recording movement informationrepresentative of said different path on the recording medium in therecorder to which said cart can be subsequently responsive, said outputsof said first and second oscillator circuits providing the recording ofinformation in said recorder means, and means in circuit with said firstand second motor means responsive to the frequencies respectively ofsaid first and second oscillators for determining movement of said firstand second motor means, wherein said frequency responsive means eachcomprise an active filter circuit including an operational amplifierhaving a pair of differential inputs and a pair of feedback impedancescoupled respectively thereto, a first RC series circuit for coupling afilter circuit input to an inverting input of said amplifier, and aparallel RC circuit coupled to a non-inverting input of said amplifierand across which the filtered output is taken.